There is no way to measure accurate MPG if you are using a scan gauge to figure your mileage or if you run theGen set which uses the gas from your tank.. Also when filling up, how do you know if you are topping off to the same level each time you fill when each shut off nozzle shuts off at a different level. I can usually squeeze in 2 more gallons after the shutoff occurs but do you do this every time you fill? also I have recorded 20 MPG on the scan gauge going down hill but that is only accurate for that part of the trip. So it is what it is or what ever you tell us that you want us to believe . Happy RV ing
